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Initial brake system fill and bleed - problems

jeffw@sc47

Well Known Member
I opted for the Beringer brake system for my RV-14A, all installed a couple of years ago.

A few weeks ago I started with the initial brake system fill and bleed.

Initial problem was it was not filling at all - short answer is that I found that I had plumbed the parking brake wrong - I had the in and out lines to the parking brake valve exchanged on both left and right lines - corrected that and rechecked and confirmed that all of line were plumbed correctly, two times to be sure.

Then I first filled and bled the the right side brake system. Fluid fill and pedal resistance came quickly - super - > then went to the left brake system.

On the left brake side > Went through the whole published Beringer fill and bleed procedure multiple times - no joy, not any pedal resistance. And no leaks anywhere.
Also, detached the bottom of the brake cylinder pistons from the left system side pedals and positioned level/horizontal to let any air in the cylinders to pass as recommended by Beringer.

Today, with assistance from a neighbor A&P, from the bottom (the brake caliper bleed screw) I pumped the bleeder to 18 PSI and in-sequence at every brake line fitting, bottom-to-top, confirmed that I had fluid flow by loosening the line fitting. - not a smidgen of pedal resistance??

And, yes - the parking brake is OFF.

What am I missing, what next? Oh, BTW I am holding my tongue to the left.
 
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Parking brake was definitely off when bleeding? I know it's pretty obvious but weirder things have happened! Sounds like you have checked everything else thoroughly and with two sets of eyes.
 
At 18 psi it should be forcing the last of the air out. You may have to cycle the master cylinders to help the pressure. Try that. Possibiity that the masters sat for quite a while and the pison o'rings are bypassing internally. Pump the pedals some and see if that changes anything.

Tom
 
Lots of pumping when bled

Tom,

The Beringer bleeding process instructs to do LOTS of pumping in a specific way and sequence - followed their instructions, four times completely, left and right.

Contacted their tech support (Billy, at their US main office - here in Greenville, SC) and followed a few additional things to do:
1- Confirm that parking brake - OFF. > DID THAT.
2- Reconfirm that all of the brake line hoses are arranged/connected correctly. > DID THAT.
3- Disconnect the bottom of each brake pedal master cylinder and position it horizontal with the connection ports-UP, to allow any air in the cylinder to flow through. > DID THAT.
4- Pressure up the system with the pump, and then, in-sequence from the brake caliper up - loosen each connection to ensure that fluid flows out. > DID THAT.

Did all 1 through 4 and still NADA.

Will get Billy at Beringer to come visit and scratch his head on site with me to figure this out.
 
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Bleeding brake hint

Here is a way that works..

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Jeff,

The shop at Laurens just had the identical problem with a Cherokee with dual brakes and a parking brake. Multiple A&Ps tried to help with no success. They finally found the problem and got it corrected. I'm going to the airport this morning and I'll ask what they found..


Rob
 
No spills ...

A few more details on how ...


1) Just fill the reservoir full..

2) Then fill the hypodermic from the reservoir..

3) Inject...

4) Go to step 1 till system full..



Will never have an overflow mess ..
 
Update - filled and pressured, more to do

Here's the story.

Two hurdles discovered and fixed:
1- The first was that I had plumbed the parking brake backwards - the in and out lines reversed - fixed. Still can't get flow to fill.
2- Second - the parking brake on/off lever was in the ON position in both positions. The Beringer install instructions did not include directions on what the ON/OFF positions are or where to find that information - so I made an ASSUMPTION that was wrong and the ON/OFF I had position was actually ON in both settings - fixed.
NOTE: The parking brake ON/OFF diagrams for all of their parking brakes is in the products catalogue but not referenced in the install instructions.

After that both left and right brake systems filled fast BUT -

On advise from Beringer, I had to disconnect the bottom attach point of each of the four master cylinders and position them horizontal while pressuring the system from the bottom, then reattach the cylinders to the bottom of the pedal and go through the Beringer bleed procedure. Finally got stiff brake pedals. But, after filling the left side, those pedals did not get stiff until I had filled the right side, and both side's pedal got stiff but not hard. Each side required that I pumped at least three full over-flow bottles before each side got stiff.

Trevor, Billy and Jordan (the Three Beringer Amigos) visited yesterday afternoon to ponder what was going on.

The consensus was that the system is designed with a brake fluid reservoir being located and attached on the left and right brake systems separately - both left and right fluid lines isolated from each other. It may be that the install on an RV with the two sides being plumbed to the same single fitting at the firewall reservoir allowing fluid to overflow across systems. Not having clear fluid lines doesn't provide an opportunity to observe what the fluid is actually doing but we think that fluid has to be crossing over, but why that creates a problem is not clear.

The amigos think that the brake master cylinders design just does not like the arrangement that allows the fluid to cross over to the other side's system. It looks like I may have to repeat detaching the bottom of the cylinders from the pedals and position horizontally at least a couple more times with pressure in the system to get all of the air out.

On the downhill side of the brake system filling and bleeding process now.
 
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DIY Solution for Overfilling Brake Fluid Reservoir

I make this little "gadget" that goes in the BF Reservoir when bleeding the brakes to automatically maintain the correct "head space" when there is fluid overflow during the bleeding process.

Pretty self explanatory - when the fluid rises to the level of the bottom of the ez-fill tube, it (fluid) continues up through the tube and out to the discharge outlet (connected to a clear vinyl tube - to monitor removal of entrained air). Once the fluid rises to, and "covers" the inlet, the remaining space above is slightly pressurized (to fluid pressure), and remains to yield the necessary "head space" for an operating system.

The fitting shown has a 90* elbow to clear any potential clearance issues with the cowling hinge line. If conditions permit, a straight thru configuration works just fine.

I silver braze all connections, then bead blast to get rid of "overrun" - then paint.

YMMV - but this works for me.

HFS
 

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Glad you are making progress, Jeff. In the way of encouragement, we used Beringer brakes and parking brakes on our two RV-14s, and after filling them from the bottom, have not had any problems. The brakes are great! You’ll get there. ;)
 
MED - Similar experiences?

Med,

Did you have the same or similar experience as I described with the multiple and lots of pumping up and bleeding with multiple full over flow bottle fills?

Bled them again this morning and raised the pedal cylinders horizontal and got solid hard pedals. Will check again tomorrow morning and see if they're holding.
 
I make this little "gadget" that goes in the BF Reservoir when bleeding the brakes to automatically maintain the correct "head space" when there is fluid overflow during the bleeding process.

Pretty self explanatory - when the fluid rises to the level of the bottom of the ez-fill tube, it (fluid) continues up through the tube and out to the discharge outlet (connected to a clear vinyl tube - to monitor removal of entrained air). Once the fluid rises to, and "covers" the inlet, the remaining space above is slightly pressurized (to fluid pressure), and remains to yield the necessary "head space" for an operating system.

The fitting shown has a 90* elbow to clear and potential clearance issues with the cowling hinge line. If conditions permit, a straight thru configuration works just fine.

I silver braze all connections, then bead blast to get rid of "overrun" - then paint.

YMMV - but this works for me.

HFS

Good Idea!! and it really works too.

I do the same thing for the same reason. The difference is I use a brass adapter to 1/4" OD poly tubing and drill the inside so the tube will go all the way through. No brazing needed, and I loosen the B nut and allow the fitting to spin when installing. It is directly attached to a small bottle to catch the over flow, otherwise the little bottles always get away and spill. It hangs down where I can see it when operating the bleed valve and pressure cup.

I use a slightly modified less-than-$10 2 liter hand pump garden sprayer to pressurize from the bottom.
 
Same better, a bit simpler

After the reservoir is filled and the system bled, I pull about 1.5 ounce of fluid up out of the reservoir with a syringe to create the head space.
 
Med,

Did you have the same or similar experience as I described with the multiple and lots of pumping up and bleeding with multiple full over flow bottle fills?

Bled them again this morning and raised the pedal cylinders horizontal and got solid hard pedals. Will check again tomorrow morning and see if they're holding.

We set up an overflow bottle at the reservoir and filled from the bottom of each side with a garden sprayer. We did disconnect the brake cylinders at the rudder pedals and oriented them horizontally to help clear any air, as someone on the forum suggested. Then, as you did, we used a syringe to create a little headspace in the reservoir. All in all, it didn’t take very long and we both ended up with solid brakes. :)
 
I'll post this again--

My friend Ray Ward, many time builder of all sorts of planes, uses this bleeder he bought from Amazon, Used with your compressor and a regulator, bleed from the caliper bottom. Certainly forces all the air out.

Tom
 

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